SE 20W. What tube?

[Hojvaelde]

Hello

One of my friends arsked me to build a amplifier.

He wanted 20 watt and SE. Two monobloks. Separate PSU.

I think 20 watt is OK because in the moment he is using a 22 watt PP amplifier he has borrowd and the room is +25 sqrm.

BUT 20 watts SE is not easy and he want a good sound.

I think the OPT must be Lundahls and the capasitores Jensen but what schematic/tube type can You recommend.

PSE KT88 can do 20 watt, but other excotics type as 211, 811, 813, 845, SV572 or 6C33 can also do 20 watt.

Help ( experience ) wanted.
If it sound well I think I will build two to my self to :-)

Benny

[blacklight]

Seriously, that's a LOT of power for such a small room especially if the speakers are fairly efficient. Anyhow, you might want to take a look at KR tubes. They claim 22W class A for the 842VHD model and even 20-24W for their 300B models. Not cheap though (~500€/pair). And of course, you need lots of voltage.

[Alain Dupont]

Hojvaelde,

>> 20 watt and SE
>> PSE KT88 can do 20 watt, but other excotics type as 211, 811, 813, 845,
>> SV572 or 6C33 can also do 20 watt.

Wouahhh > 20 watt and SE ; is this first condition highly important ? Or 18 watts
could do it?

For SE its douable with 2 * 6C33C-B ==> 32/36 watts
with 1 tube it's only 16/18 watts max {}
see schematics from Ari Polisois: http://www.valvediy.com/simplexpg1.html
{I am building the Simplex } Ari published last year a SE with a triplet
of 6C33C-B for 45 watts on AudioXpress.
http://www.jogis-roehrenbude.de/Lese...schreibung.htm

>30 watts the problem is a custom OPT, price will be high.

SE with 300B:
AUDIO NOTE CONQUEST 18W Classe A with 2 * 300B in //

SE with 211 tube
ONGAKU Audio Note Single Ended classe A 25 with 211 tubes
{> 850 volts ; it's the Best! in all classes!}

Push-Pull: Attention here you get power but loose the flower of second harmonic distortion for 3rd harmonic distortion and negative feedback...

On the Push-Pull side 6C33C-B at 70 watts
See the articles by Menno at plitron:
http://www.plitron.com/PDF/PB/specs/pat4144-00.pdf

For the 300B Push-pull at 30 watts
Push-Pull: http://www.plitron.com/PDF/PB/specs/pat4150-00.pdf

EL34 Push-pull at 25 watts
http://www.plitron.com/PDF/PB/specs/pat4148-00.pdf

It's my own view for SE ; perhaps someone can lead to other choices.

Alain.

[rcavictim]

813 in SE ultra linear is easy to drive and simple PSU. You would end up with an amp like a SE 6BQ5/EL84 with lot's of power (25 watts easy). I am awaiting output xfmers from Handwave for this proposed experiment myself. For the past two years waiting!

There is a Euro version of the 813 without a plate cap. I forget the number. Use that one.

[KimBOlesen]

Hi Benny

Look at my homepage www.micro-io.dk. I have used the 6c33 and i get 36Watt from them with homemade transformers.

Best regards Kim Olesen

PS: du kan finde mit telefon nummer på krak (se under feedback på min hjemmeside) hvis du vil vide mere.

[edl]

think 20 watt is OK because in the moment he is using a 22 watt PP amplifier he has borrowd and the room is +25 sqrm.

An 5-10W SE amp relatively will be as loud as a 20W PP amp.

I would build parallell-SE EL84. That gives 10W. And EL84 sounds as nice as the gold-priced "super-audiophile" DHT-triodes. Anyway the quality of the amp depends more on the output transformer, PSU, driving. The type of the output tube isn't the first.
Or you could try 6L6GC, KT88, EL34, 807 etc... These are popular, cheaper, but also good-sounding tubes.

Regards,

[Giaime]

I would do PP

Seriously, 807 PSE sounds VERY good. So does KT90, talking about unusual tubes. Or, if you can find any, EL156

Also medium-small transmitting triodes sound good. A normal 845 SE is pretty straightforward, iron is everywhere and you'll get 20W without stressing the tubes.

However, given the price of China 845 (which sound good), I would go A2 aka Powerdrive (www.tubelab.com) and get the full 40W.

Maybe you could scale down it and use 300B instead

[rcavictim]

Before this thread drifts into a discussion about the merrits of SS versus tube amplification let me remind some that the original poster has asked a direct question. The question, as I read it, is about single ended options to produce 20 watts RMS because a friend already experiencing 22 watts push-pull has requested Single Ended.

Originally posted by Hojvaelde
Hello

One of my friends arsked me to build a amplifier.

He wanted 20 watt and SE. Two monobloks. Separate PSU.

I think 20 watt is OK because in the moment he is using a 22 watt PP amplifier he has borrowd and the room is +25 sqrm.

BUT 20 watts SE is not easy and he want a good sound.

I think the OPT must be Lundahls and the capasitores Jensen but what schematic/tube type can You recommend.

PSE KT88 can do 20 watt, but other excotics type as 211, 811, 813, 845, SV572 or 6C33 can also do 20 watt.

Help ( experience ) wanted.
If it sound well I think I will build two to my self to :-)

Benny

Earlier I offered a SE penode 813 as an option because it is S I M P L E to implement and I'm told sounds good.

As further contribution I can suggest that 6080's in parallel A1 ultrafeed and paracoupled can sound mighty good and can be set up without paying full fare for an expensive outoput xfmer like a Lundal. I am slowly working on just such a 20+ watt design on the bench now which employs four bottles per channel (8 triodes in parallel) and it sounds fabulous although only the output stage has been prototyped so far.

I also question that the caps "must" be Jensen. There are very top sound quality caps available that do not carry boutique names, and therefore are not burdened with boutique prices.

[Fuling]

A single PL519 will deliver 15-16 good sounding watts if you drive it by the screen grid.
B+ only needs to be around 400-450V

[agent.5]

i am currently building one with eimac 250tl

also you may consider using gm70 tube and take a look at the site gm70



http://groups.yahoo.com/group/GM70/